The term dermatitis is often used interchangeably with eczema. However, atopic dermatitis (eczema) is an endogenous inflammatory skin condition, while CD is induced by exogenous factors.
Contact dermatitis (CD) accounts for 70-90% of all occupational skin diseases. It is an inflammatory skin condition induced by exposure to an external irritant or allergen. In a recent cross-sectional study of 12,377 subjects from 5 European countries, a randomly selected group of 3,119 patients underwent patch testing. The condition can have a detrimental impact on personal and social relationships and quality of life, and even threaten employment.
What are the different types of contact dermatitis?
Irritant CD is a non-immunological response that occurs as a consequence of direct damage to the skin by chemical or physical agents, faster than the skin itself is able to repair it. In almost 80% of cases, CD is irritative. The most common main causes of irritative DC are soaps, detergents, water, solvents, cutting oils and food ingredients. The most commonly affected are the hands, mainly the moist spaces of the fingers and the face.
Allergic CD comprises 20% of CD cases. It is a delayed type IV hypersensitivity reaction to an external allergen, which occurs only in individuals who have been previously sensitized. Reexposure to the allergen triggers the circulation of memory T messenger cells that elicit an immune reaction that causes skin inflammation, typically within 48 hours.
How is contact dermatitis different from eczema?
The term dermatitis is often used interchangeably with eczema. However, atopic dermatitis (eczema) is an endogenous inflammatory skin condition, while CD is induced by exogenous factors. Clinically, it is difficult to differentiate them, and both conditions can coexist, especially eczema of the feet and hands.
CD is suspected in patients with atopic dermatitis who do not respond to treatment (i.e., despite the use of potent or ultra-potent topical corticosteroids, with emollients and soap substitutes) or who suffer a flare when treatment is discontinued. treatment or, the distribution of your disease is unusual. For example, chemicals in clothing can cause changes in the armpits, groin, and feet, suggestive of allergic CD.
| Clinical manifestations of atopic dermatitis, irritant contact dermatitis and allergic contact dermatitis | |||
| Atopic dermatitis | Irritant contact dermatitis | allergic contact dermatitis | |
| Incidence | Common: affects 2-10% and 15-20% schoolchildren+ | It can occur in anyone. 80% DC | It occurs only in sensitized people. It is 20% of the DC |
| Starting age | Commonly childhood | Any age; common in adults | Any age; common in adults |
| Personal or family history of atopy | Present | Frequently present | May or may not be present |
| Symptoms | Dryness, peeling, itching | Itching, burning, stinging | Itching, burning, stinging |
| Clinical distribution | Facial, extensors in childhood. Flexion zones in childhood and adolescence. Flexion zones in adults and adolescents | Located in contact sites (especially hands and face) | Mainly confined to contact sites but can spread remotely |
| Pathophysiology | Due to the complex interaction of genetic factors, environmental, immunological and defects in skin barrier function. Mainly associated with Th2 cells, cytokine-mediated disease | Non-immunological reaction
Caused by direct damage to the skin by chemicals or physical products | Immune reaction
Delayed T cell-mediated hypersensitivity reaction, type IV to an external allergen
|
| Start after exposure |
_______ | Minutes to hours
No prior exposure required | 8 a.m.-4 p.m. Commonly 48 hours. Requires prior exposure |
| Evolution | Chronic with remissions and exacerbations | Prompt recovery with suspension of the irritant | May persist despite suspension of the allergen |
| patch test | Often positive but interpret according to the story |
Negative |
Positive |
Who suffers from contact dermatitis?
The increasing incidence of CD due to various allergens is attributed to lifestyle changes and the increase in consumer products. More thorough investigation of allergens with patch testing led to the detection of more cases of allergic CD. As a result of some chemicals being recognized as the contact allergen, they are discontinued and may be replaced by other products, which in turn could induce contact allergy, so the repertoire of potential allergens is constantly evolving.
Data from the THOR-EPIDERM project, a national occupational health surveillance system, has shown that the professions with the highest risk of developing CD are florists, hairdressers, beauticians, cooks, metal workers and other manufacturing and occupations related to the health care. Healthcare workers appear to be at risk as a result of frequent handwashing.
A recent survey showed a prevalence of hand dermatitis of 4% in healthcare workers, of whom 98% suffer from irritative CD. Women are more likely to suffer from allergic CD than men. Allergic CD is not uncommon in children and is increasing. The presence of eczema increases the risk of irritative DC due to disruption of the skin’s barrier function. A history of atopy possibly increases the risk of allergic CD, although more studies are needed to clarify.
How is contact dermatitis diagnosed?
Contact dermatitis is classically localized to contact sites, but irregular or diffuse rashes may also arise.
Clinical evaluation
The patient’s history can reveal potential allergens and irritants and guide further investigation and management of the disease. Questions should be asked about the pruritus, the evolution of the disease, the relationship with sun exposure, the response to treatment, and the personal or family history of atopy. Specifically, ask about the use of hair dye, cosmetics, jewelry, skin care products, and oral or topical medications, including complementary treatments. If the dermatitis does not respond or worsens after use of topical corticosteroids, the patient may have sensitivity to the corticosteroids or other ingredients in the topical preparation.
Occupational causes are suspected when symptoms improve during time away from work. Ask specific questions about the workplace, such as the availability of personal protective equipment (e.g., proper glove selection). The “hobbies” associated with DC are gardening, carpentry, metal carpentry, photography, swimming and painting.
The clinical characteristics of CD in the acute phase are: pruritus, erythema, dryness and peeling, but vesicles and blisters may develop. With chronic disease, lichenification and fissures may occur. A recent study by the Danish Contact Dermatitis group showed that lesion morphology is often unreliable in predicting whether the cause is allergic, irritant or endogenous.
CD is classically localized at contact sites, but irregular or diffuse eruptions may also arise. The areas most prone to CD are the hands, face, eyelids, neck, scalp, armpits, lower extremities, feet and anogenital area. CD appears in places exposed to the sun and air. Photodistributed DC is what appears in areas of maximum exposure to sunlight and is therefore involved in photosensitivity eruptions. Signs of sunlight-induced CD include involvement of specific limited areas, such as under the chin, nose, and behind the ears. Airborne CD characterizes a unique type of CD originating from dust, aerosols, pollen, or chemicals volatilized into the air by gases or particles, without manipulation of the allergen.
What you need to know • At risk: florists, hairdressers, beauticians, cooks, metal workers and other manufacturing occupations and health-related professions • Diagnosis is clinical or with patch testing in some cases. • Interpret patch test results based on clinical history to determine relevance • Avoidance of allergens and irritants is an important aspect of self-management • Therapeutic options are: topical corticosteroids, topical calcineurin inhibitors, and systemic therapies, if necessary. |
When should the studies be carried out?
Anyone with suspected DC should be referred to a dermatologist for skin patch testing. These tests are the gold standard for the diagnosis of allergic CD. Generally, the diagnosis of irritative CD is made by exclusion, when patch tests for allergic CD are negative. Irritant CD is generally limited to the site of contact with the irritant. For example, contact with mild irritants such as soap or detergent can, over time, cause dryness, itching, and cracking of the hands from repetitive washing.
The dimethylgloxime test (nickel test) is very specific (Reported in 97.5% of cases); It is a rapid test that can be performed in the clinic to detect nickel released by metal objects.
Patch testing should be considered for: • Possible cases of allergic CD, in which the diagnosis is not clinically evident. This may include sudden onset CD, especially if there is no history of eczema in an adult. • Dermatitis with an unusual distribution, including one that takes a very localized form (such as the face and neck, eyelids, hands and feet). • Dermatitis related to occupational exposure. • Other types of severe chronic dermatitis (eczema) that do not improve with treatment and may be caused by unsuspected contact allergens. For example, stasis of the hands and feet, seborrheic dermatitis or discoid (numular) eczema. |
Asymptomatic patients are not patch tested unless they have been exposed to significant allergens in the past. For example, referrals for metal patch testing are increasingly common in secondary care prior to joint replacement surgery, to avoid any problems with metal prosthetic implants. Patch tests are not routinely performed to screen for food allergies.
How useful are patch tests?
A large-scale multicenter prospective observational study demonstrated that patch testing produces an improvement in quality of life, since it allows early diagnosis of the etiology through the identification of allergens and allows treatment to be initiated before the disease develops. chronicle Studies have shown the importance of patch testing in children, which is of great help when the clinical presentation is suggestive of allergic CD. Although they vary according to the allergen tested, data from common series analyzes suggest a sensitivity of 0.77 and a specificity of 0.71 for these tests.
The authors clarify that patch testing does not tell us what exposure caused the contact allergy or what type of exposure can be tolerated. Potential complications are the activation of an atopic dermatitis flare; rarely the induction of intense reactions that can cause scarring and, occasionally, the induction of sensitivity to a new allergen. Isolatedly, type 1 hypersensitivity reactions, including anaphylaxis, have also been reported. Therefore, patch testing should be performed in an environment with access to resuscitation equipment, having previously performed the full history, to decide if patch testing is appropriate.
patch test
|
What does a positive patch test mean?
Not all positive reactions are of clinical importance. Some may be irrelevant cross reactions. The North American Contact Dermatitis group’s study of 4,238 patients undergoing patch testing in 2011-12 reported that 63.8% had at least one positive reaction but only 48% resulted in a final diagnosis of allergic CD. Patient history is crucial to understanding the clinical relevance of positive patch reactions and making the diagnosis of allergic CD. Investigating the composition of the products to which the patient has been exposed is another strategy to establish the relationship.
Interpreting patch test results is complex. The British Association of Dermatologists guidelines indicate that a positive patch test result is clinically relevant if the patient has been exposed to the allergen during the current episode of dermatitis and symptoms improve upon cessation of exposure. Other possible explanations for the positive results are:
• past relationship─if in the past there was an episode of dermatitis due to exposure to the allergen, such as allergic CD due to contact with an earring, due to nickel allergy.
• Unknown relationship─ unclear if exposure is current or past
• Cross reaction─positive test reaction is due to cross reaction with another allergen.
False positive reactions may result from the use of irritating or allergenic substances in higher potentially irritating concentrations or from performing the patch test on skin with active eczema. False negative tests can occur when allergen concentrations for testing are too low, if there has previously been exposure to ultraviolet light, the patient is receiving immunosuppressive therapy, or methodological errors have occurred, such as failure to comply with delayed readings. or insufficient occlusion.
If a reaction is negative but the history is highly suggestive of an allergic cause, then the patch test or serial dilution patch test should be performed to clarify the nature of the reaction. In some cases, exposure to a contact allergen can clearly explain dermatitis. In reality, the cause of dermatitis is often multifactorial.
How is contact dermatitis managed?
Self-care
The definitive management of CD is the identification and avoidance of the underlying cause. Advise patients to avoid exposure to allergens and irritants at home and in the workplace. Personal protective equipment such as gloves and masks can minimize future exposures to the contact allergen.
In some cases, dermatitis can lead to occupational redeployment or loss. Patients should be encouraged to explain their diagnosis to their employer and seek advice from the health department at their workplace.
Provide patients with written information about all identified allergens, including the name of the allergen, its synonyms, its common use, and examples of the types of products that may contain it. Advise patients to read the ingredient lists of all their skin care products before application and when purchasing new products. The ingredients of a product are usually listed on the label or on the packaging or information leaflet.
Advise patients that if they want to try a new skin care product, they can perform a repeat non-occlusive test before using it. They should apply a small amount of the product to the volar aspect of the forearm, 2 times/day, for 1-2 weeks. If any eczematous reaction occurs, the product should be avoided.
Topical treatment
| Topical treatment of contact dermatitis | |||
| Topical treatment | Mechanism of action | Application mode | Adverse effects |
| Emollients | Restore skin barrier function, prevents painful fissures | Apply frequently during the day and before going to bed. A lighter moisturizer can be applied during the day and more rich in lipids, fragrance-free, greasy emollient at night It should be applied generously to all affected areas. | May cause acne or folliculitis Some emollients may cause irritating reactions. |
| Topical corticosteroids | Anti-inflammatories and immunosuppressants | 1-2 times/day on affected sites; 4-6 weeks initially, reevaluate. If it improves, gradually reduce the frequency, but may need therapy 2 times/week, in maintenance if severe. | Skin atrophy, tachyphylaxis, systemic absorption causing adrenal suppression (very rare), steroid-allergic DC induction |
| Topical calcineurin inhibitors | Immunomodulator | 1-2 times/day on affected sites for 4-6 weeks initially, then reassess | Mild to moderate burning or stinging, erythema, concern about long-term risk of skin carcinogenesis (sun protection advocacy) Avoid active skin infection |
| Others: K permanganate compresses | oxidizing agent with disinfectant, deodorizer, and astringent properties | It is used for oozing or infected eczema. Dissolve 400 mg of the tablet (Permitab) in 4 L of water to make 1:10,000 solution. Soak affected areas for 10-15 minutes. Use 1-2 times/day until lesions dry (usually 2-5 days) Use concomitantly with topical steroids and emollients | Redness, irritation, caustic burns Dye clothes, fabrics, and ceramic sinks |
Regular emollients are recommended to improve the skin’s barrier function. A wide range of emollients are commercially available. The evidence base is too weak to recommend any particular emollient, but an essential factor to consider is patient preference. Lipid-rich emollients can accelerate healing after experimental skin damage, which favors their choice, particularly for nighttime use.
Likewise, to minimize irritation, the use of soap substitutes is recommended. A recent Cochrane review that included 4 randomized controlled trials of barrier creams versus no workplace intervention showed fewer new cases of occupational irritant CD using barrier creams. Statistical significance was not achieved, probably reflecting the fact that more well-designed clinical trials are needed.
The efficacy of topical corticosteroids for the treatment of allergic CD is well documented. The evidence is less clear for irritative CD. According to consensus guidelines on the management of chronic eczema (a common manifestation of CD), the topical treatment of choice after emollients and soap substitutes is a topical steroid. Topical steroids are effective in the short term, but inhibit stratum corneum repair and induce skin atrophy, which may interfere with long-term recovery.
Anecdotal evidence suggests that intermittent treatment with topical corticosteroids or alternating a topical corticosteroid with a topical calcineurin inhibitor may reduce adverse effects, but data on the long-term safety of this approach are lacking. The optimal duration of treatment with topical corticosteroids is unknown, but from clinical experience the authors recommend an initial treatment period of 4-6 weeks with a potent topical steroid, followed by subsequent review.
Evidence shows that intermittent and long-term mometasone furoate is safe and effective for the treatment of hand eczema for up to 36 weeks. Evidence has also shown that the risk of recurrence of chronic hand eczema is reduced using a very potent steroid (clobetasol propionate) compared to a moderately potent topical corticosteroid.
For all cases of moderate to severe dermatitis, the potency and period of use of topical steroids should be adjusted according to the severity of the condition. Currently, topical calcineurin inhibitors are approved as second-line medications for the treatment of atopic dermatitis when topical steroids have failed or if there is a serious risk of adverse effects, including irreversible skin atrophy. These principles also apply to the treatment of CD, although the use of topical calcineurin inhibitors is off-label.
Topical calcineurin inhibitors should be considered especially for sites prone to atrophy induced by long-term steroid use, such as the face and neck.
Adverse events such as pruritus and burning are common with calcineurin inhibitors, but are usually transient. In a randomized comparative study of patients with allergic CD of the hands, the efficacy of tacrolimus 0.1% was found to be similar to that of mometasone furoate ointment 0.1%.
Systemic treatment
Occasionally, patients may require systemic treatment. In that case, the patient should be under the care of a dermatologist. It is possible that systemic corticosteroids may be required for short periods during the acute phase of severe CD. Treatments with psoralen combined with ultraviolet light (PUVA), narrow-band ultraviolet B light, or systemic immunomodulators (e.g., methotrexate, cyclosporine, azathioprine) may be second-line options for patients with chronic dermatitis who do not respond to treatment. conventional topical therapy. Alitretinoin is licensed for the chronic treatment of severe eczema. Although immunomodulators are used to treat chronic skin diseases, each has its own associated adverse effects.
What is the prognosis?
The prognosis depends on the patient’s ability to avoid the allergen or irritant. A recent study with a follow-up of 7-14 years showed that 40% of patients with hand eczema at work had not experienced the disease in the last year. Risk factors for continued dermatitis were prolonged duration of hand eczema before diagnosis, respiratory atopy, skin atopy, and continuing in the same job. Inform patients about the possibility that CD may persist and require prolonged treatment, even after initial treatment and workplace modifications.
